Adjusting mechanism for geometrical instruments and the like.



l C. W. THOMAS & H. D. ORTH.

`ADJUSTING MECHANISM FOR GEOMEVTRICAL {NSTRUMENTS AND THE LIKk.l

APPLICATION FILED AUG.9, |916- v Patented July 24,1917.

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CHARLES W. THOMAS IND HERBERT D. ORTI-I, 0F MADISON, WISCONSIN.

ADJUSTING MECHANISIVI FOR GEOMETRICAL INSTRUMENTS Application filed August 9, 1916.

To all al1/0m 'it may concern.'

Be it known that we, CHARLES W. THOMAS and HERBERT D. ORTH, both citizens or the United States, residing in Madison, county of Dane, and State of Visconsin, have in vented certain new and useful Improvements in Adjusting Mechanism for Geometrical Instruments and the like; and we do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The adjusting mechanism of the present invention is useful in connection with tools, geometrical instruments, and the like, where two members are to be quickly adjusted toward or from one another, and particularly where the adjusted members may need a supplemental and more accurate final ad* justment. This is the case in geometrical instruments, suoli as calipers, Compasses, bow pencils, and the like, for with these instruments it is often desirable to quickly change the span of the. leg members and then, by more accurate adjustment, to bring them slowly to an exact predetermined distance apart. A

It is an object of the present invention to provide an adjusting mechanism comprising a rotatable member having frictional engagement with one of the members to be adjusted and threaded engagement with the other, this rotatable member being axially movable to rotate more freely when a quick or large adjustment is to be made, and then to hold said members in the adjusted position while permitting the liner or more accurate adjustment to be made by slow manual rotation of the rotatable member.

Various other objects and advantages will be made clear by the following description, which is to be taken in connection with the accompanying' drawings, wherein is illustrated one complete embodiment of the invention and various modiiications of some of the details.

In the drawings Figure l is an elevation partly in section or' a bow pencil constructed in accordance with the present invention;

Fig. 2 is an enlarged sectional elevation of the rotatable member whereby the legs of the instrument are adjusted toward or from one another;

Specification of Letters Patent.

AND lII-IIE! LIKE.

Patented July 211i, 19t '1? serial No. 113,851.

Fig. 3 is a detail oi3 the auxiliary bearing at one end of the rotatable member;

Fig. 4 illustrates the swinging nut for the other end of the rotatable member;

Fig. 5 is a modified pivotal bearing for the thumb piece near the threaded nut;

Figs. 6, 7 and 8 show a modiiied form of bearing for the right hand end of the rotatable member of Fig. 2;

Fig. 9 illustrates a :further modification;

Figs. l0 and l1 are respectively a sectional elevation and an end view of a still further modification of this part of the apparatus; and

Figs. 12 and 13 show additional modifications.

In the construction illustrated in Fig. l, the members to be adjusted toward or from one another are the legs l and 2 of the bow instrument. These are pivoted to one another in usual manner at 3, and they extend beyond this pivot for engagement with a spring 4: to which the handle 5 of the instrument is attached. Spring l presses inward on the upper extensions of these legs and so constantly tends to spread their lower or free ends. There is provided a rotatable member 6 having multiple screw threads of high pitch or equivalent slots or grooves, and this has threaded engagement at one end with a nut 7 seated in leg member 2 and free to swing therein about a transverse aXis so that as legs l and 2 move toward or from one another, the nut may adjust itself to the changing angular relation or rotatable member 6. The adjacent end of the rotatable member is provided with a ball 8 terminating in a pivot point 9 and loosely enveloped by the socket of a thumb piece l0. Pressure on the thumb piece will cause it to seat on the pivot point 9 and release the fricyiorllal engagement between the socket and In the modification illustrated in Fig. 5, the thumb piece ll has its socket swaged inward to engage a cone l2, which takes the place of ball 8 of Fig. l, and within the socket of the thumb piece is a loose ball 13 which can be brought into action by pressure on the thumb piece and serves as a low resistance pivot in much the same way that needle point 9 of Fig. l may serve.

The other end of the rotatable member is adapted to rrictionally engage leg member l while remaining free to swing with re spect thereto, so lar as is necessary when the leg members are ad] usted toward or trom one another.y rillus trictional engagement may be etiected by means ot a spherical ysocket in leg 1, within which :tits a spherical enlargement 14 forming a part ot rotatable member 6. As shown in Fig. 2., this spherical enlargement lei carries a needle point Co-aXial with the threaded portion ot the rotatable member. J ust opposite this needle point is a transverse bar 16 mounted in ears 17 on leg member 1 (Fig. 3), and this transverse bar 16 has a small recess spaced somewhat from the end ot needle pointl but into which the needle point may be received when the rotatable member is shifted longitudinally and with respect to leg 1. Bar 16 and its eolperating pivot 15 therefore form an auxiliary bearing` offering low resistance to rotation ot the rotatable member, this auxiliary bearing being adapted to come into action when the rotatable member is unseated i'rom its rictional engagement at the ball and socket connectiony with leg 1.

The rotatable member includes an adjustg ing disk 18 preferably dished, as shown, and mounted near leg disk that the liner adjustments of the instrument may be made by slow manual rotation of the rotatable member t3 within its nuty 7. By mounting` the disk near leg 1, these adjustments can be made conveniently and with but small tendency to swing the pencil point of one leg about the needle point et the other while the adjustments are being made. The dished 'torni of the disk gives adequate clearance for leg 1 and also serves to accommodate the opposing engagement of leg 2,

The operation of the device is as :follows:

To close the legs of the instrument, a slight pressure is brought to bear upon the tree ends of members 1 and 2. 141 to move a slight distance trom its socket and brings needle point 15 into contact with cross-bar 1G. A slight further pressure on the legs in the direction to close them will result in a turning or spinning of the rot-atable member 6. Thisy isy due to the steep pitchy of the threads on the rotatable mem-y ber. The span having thus been adjusted to the approximate radius and enlargement 111 being re-seated by spring e, all finer adjust ments are made by manually turning disk 1S.

llVhen it is desired to spread the legs apart, a slight pressure on thumb piece 10 causes it to seat on needle point 9 and to move ball 1e out of ifrictional engagement with its socket in leg 1, at the saine time seating needle point 15 on cross-bar lythereby re ducing the rictional resistance to ther turning of rotatable member 6. The spring e then acts through the legs and nut 7 to turn or spin the rotatable member and a greater (Fig. 2), is provided with 1. lt is by this adjusting wherein the swinging nut 7 is mounted.

rllhis causes ballk span is the result. Releasing the pressure on thumb piece 10 causes ball le to be drawn again into its socket vhere it acts as a brake to further turning ot the rotatable member. Fine adjustments may. then be made by disk 18 as before.

ln the modification illustrated in Figs. 6, 7 and 8, the enlarged end of the rotatable member, instead of being spherical, as at 14: a cone 19 which is received within a cone-shaped socket provided in a transverse member 20. lllember Q0 has a cylindrical exterior, as indicated. in elevation (Frg.` 7), and can be slid into position from the side of leg member l1, as indicated in Fig. S. T his V member 2O is, however, in two parts, and includes an independently movable slab 21 which serves as a cover for the socket of cone 19 and has a transverse slot into which the pivot point 22 of the rotatable member may move when the rotatable member is shifted axially to unseat cone k,19 from its socket. By having slab Z1 movable independently of the other part of transverse member 20, the structure is easy to assemble, and once assembled is not likely to get out et adjustment. The operation of the cone and of the auxiliary bearing afforded byneedle pointQQ and slab 21, is essentially the same as ball le, and the auxiliary bearing of Fig. 2.

ln the modification illustrated in Fig. 9, a ball 23 seated within the end of the conical enlargement of the rotatable member takes they place of the needle point 22 of Fig. G in furnishing a pivot about which the rotatable member may turn with low rictional impedance. Y

inthe modication illustrated in Figs. 10 and 11, a fiat plate screws to leg member 1 serves in place of transverse bar 16 ot Fig. 2 in receiving the needle point 15 ot the rotatable member.

rln Fig. 1Q the loose ball 25 takes the place of needle point 15 (Fig. 10) in forming the low resistance pivot or auxiliary bearing for the rotatable member.

ln Fig. 13 the needle point 15 ot Fig. Q ,is replaced by a larger and moreblunt projection 26 which, while offering the necessary lowfimpedance to rotation, is at the same time somewhat more rugged than the needle point and more resistant to abuse.

Although the embodiment of the present invention particularly illustrated in the dra-wings is a drafting instrument, we are aware that our invention is applicable to other types o'l' geometrical instruments, and even to other classes oi tools and the like, where thereis desired a quick adjustment of two members witheapacity for a final and more accurate adjustment by subsequent manual manipulation.

We have illustrated certain permissible variations in details of the embodiment 24 fastened by suitable iso Lacasse herein described, and We contemplate such changes in details and in arrangement of the component elements as may be Within the spirit of our invention as defined by the appended claims.

lle claim:

1. In combination, a pair of members to be adjusted toward or from one another, a rotatable member having frictional engagement with one member of said pair and threaded engagement with the other, said rotatable member being axially movable to rotate more freely when said pair of meinbers are to be adjusted.

2. In a geometrical instrument, the combination of a pair of members to be adjusted toward or from one another, a rotatable member having threaded engagement with one of said pair of members and having at its other end a ball and socket connection With the other of said pair of members, a pivotal bearing for said rotatable member and means for shitting said rotatable member longitudinally to bring said additional bearing into action when desired.

In combination, a pair of members to be adjusted toward or from one another, a rotatable member having frictional engagement with one member of said pair and threaded engagement with the other, and an additional bearing for said rotatable member With Which it may be brought in contact when said pair of members are to be adjusted, substantially as described.

e. In combination, a pair of members to be adjusted toward or from one another, a rotatable member having frictional engagement with one member of said pair and threaded engagement With the other, an additional bearing for said rotatable member With Which it may be brought in contact 'when said pair of members are to be adjusted toward or from one another and means for reducing the frictional engagement of said rotatable member by shifting it longitudinally to bring said additional bearing` into action when said members are to be adjusted, substantially as described.

5. In a geometrical instrument, the combination of a pair of members to be adjusted toward or from one another, a spring connected to separate said members, a rotatable member having :rictional engagement with one of said pair of members and threaded engagement with the other, an additional bearing for said rotatable member With which it may be brought in contact when said rotatable member is shifted longitudinally, and means for shifting said rotatable member to bring said additional bearing into action when said members are to be separated by said spring.

In a geometrical instrument, the combination of a pair of leg members pivoted together, one of said legs having a socket and tft a bearing, and the other having a threaded nut, a rotatable member having one end frictionally engaging one of said legs to impede free rotation of said member, said rotatable member having threads of high pitch engaging with said nut to control. the span of the legs and means for lessening the frictional impedance on said rotatable member when said legs are to be adjusted by rotation of said member through said nut.

In a geometrical instrument, the combination of a pair of leg members pivoted t0- gether, a spring urging their free ends away from one another, one of said legs having a socket and a bearing, and the other having a threaded nut mounted to swing on a transverse axis, a rotatable member having an enlarged end bearing against said socket and frictionally impeding free rotation of said member, said rotatable member having threaded engagement with said nut and a pivot at each end about which said member may rotate after said member has been shifted longitudinally to unseat said enlarged end from its socket, substantially as described.

8. In a geometrical instrument, the combination of a pair of leg members pivoted together, a spring urging their tree ends avvay from one another, one of said legs having a socket and a bearing and the other having a threaded nut, a rotatable member having a ball and socket connection with one of said legs and a pivot for seating on said bearing, said rotatable member having threads of high pitch engaging With said nut to control the span of the legs and a thumb piece having pivotal connection With one end of said rotatable member and b Which it may be shifted axially to bring the other pivot into engagement with its bearing, thereby leaving said rotatable member relatively tree to turn in its nut While said legs are being spread by said spring.

9 In a geometrical instrument, the combination of a pair of leg members pivoted together, a spring urging their free ends away from one another, one of said legs having a socket and a bearing and the other hav- 4ing a threaded nut mounted to swing on a 115 a rotatable member having its enlarged end forming with said socket a ball and socket connection frictionally impeding free rotation of said member, said rotatable member havingv threads of high pitch engaging with said swinging nut tocontrol the span of the legs, a pivot at each end of said rotatable member so disposed that when pressure is applied to one pivot, the

transverse axis,

other pivot Will come into operative engagebearing, whereby said rotatable member is left relatively tree to turn in its nut While said legs are being spread by said spring.

` away Copies of this patent may be obtained for sooket,`said rotatable member fr ve cents each, by addressing the Washington, D. 1G.

saidsvvinging nut tol control the span of the legs, a pivot at each end of said rotatable member and a thumb piece movable into Contact with one pivot, and by which pressure may be applied to unseat the ball `from its socket and effect engagement of the other pivot with said bearing, whereby said vrotatable member is lefty relatively free to turn in-its nut While said legs are being spread by said spring.

ln testimony whereof We affix our signatures.

CHAS. W. THOMAS. HERBERT D. ORTH.

Commissioner of Eatents, 

